#!/usr/bin/env bash
# Generate release notes for the next Prowl version.
#
# Usage: ./scripts/release-notes.sh [VERSION]
#
# Compares HEAD against the previous release tag, gathers commits and PR
# descriptions, and uses an LLM (claude CLI) to produce user-facing release
# notes. Falls back to GitHub auto-notes if the LLM is unavailable.
#
# Output: build/release-notes.md
# The file can be reviewed and edited before running release.sh.
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
PROJECT_DIR="$(cd "$SCRIPT_DIR/.." && pwd)"
cd "$PROJECT_DIR"

log() { echo "[release-notes] $*"; }
die() { echo "error: $*" >&2; exit 1; }

# ── Repository ───────────────────────────────────────────────────────────────

origin_repo_from_remote() {
  local remote_url
  remote_url="$(git remote get-url origin 2>/dev/null || true)"
  [[ -z "$remote_url" ]] && return 1
  local repo
  repo="$(echo "$remote_url" | sed -E 's#^(git@github.com:|ssh://git@github.com/|https://github.com/)##; s#\.git$##')"
  [[ "$repo" == */* ]] && echo "$repo" && return 0
  return 1
}

REPO="${GH_REPO:-$(origin_repo_from_remote || true)}"
[[ -z "$REPO" ]] && REPO="$(gh repo view --json nameWithOwner -q .nameWithOwner 2>/dev/null || true)"
[[ -z "$REPO" ]] && die "cannot determine GitHub repository"

# ── Version ──────────────────────────────────────────────────────────────────

if [[ -n "${1:-}" ]]; then
  VERSION="$1"
else
  VERSION="$(date +%Y.%-m.%-d)"
  suffix=1
  while git rev-parse "v$VERSION" >/dev/null 2>&1; do
    suffix=$((suffix + 1))
    VERSION="$(date +%Y.%-m.%-d).$suffix"
  done
fi

TAG="v$VERSION"

# ── Determine range ──────────────────────────────────────────────────────────

# If tag already exists, use it as the end point; otherwise use HEAD.
if git rev-parse "$TAG" >/dev/null 2>&1; then
  END_REF="$TAG"
else
  END_REF="HEAD"
fi

PREV_TAG="$(git describe --tags --abbrev=0 "$END_REF^" 2>/dev/null || true)"
if [[ -n "$PREV_TAG" ]]; then
  RANGE="$PREV_TAG..$END_REF"
else
  RANGE=""
fi

log "version: $VERSION"
log "range: ${RANGE:-<all commits>}"

# ── LLM generation ───────────────────────────────────────────────────────────

generate_llm_notes() {
  local range="$1"
  local raw_context
  raw_context="$(mktemp)"

  # Gather commit messages
  {
    echo "=== Commits ($range) ==="
    git log --pretty=format:'%s' "$range"
    echo ""
  } > "$raw_context"

  # Gather merged PR details (title + body)
  {
    echo ""
    echo "=== Merged Pull Requests ==="
    local pr_numbers
    pr_numbers="$(git log --pretty=format:'%s' "$range" | grep -oE '#[0-9]+' | tr -d '#' | sort -u)"
    for pr in $pr_numbers; do
      local pr_json
      pr_json="$(gh pr view "$pr" --repo "$REPO" --json title,body 2>/dev/null || true)"
      if [[ -n "$pr_json" ]]; then
        echo "--- PR #$pr ---"
        echo "$pr_json" | jq -r '"Title: \(.title)\nBody:\n\(.body)"'
        echo ""
      fi
    done
  } >> "$raw_context"

  # Gather diff stats
  {
    echo ""
    echo "=== Diff Stats ==="
    git diff --stat "$range"
  } >> "$raw_context"

  local prompt
  prompt="$(cat <<'PROMPT'
You are writing release notes for **Prowl**, a macOS app that runs multiple
coding agents in parallel, each in its own terminal tab.

Given the raw context below (commits, PR descriptions, diff stats), produce a
concise, user-facing changelog in Markdown.

## Rules

1. **Audience**: Prowl end-users (developers). They care about what changed in
   their day-to-day experience, not internal code structure.
2. **Include only user-visible changes**: new features, behavior changes, UX
   improvements, notable bug fixes. Skip pure refactors, test-only changes,
   CI tweaks, dependency bumps, and code-style changes unless they affect
   the user.
3. **Teach naturally**: when a change introduces a new shortcut, workflow, or
   setting, briefly explain how to use it (e.g. "Press ⌥⌘↩ to toggle
   Canvas view").
4. **Tone**: clear, professional, friendly. No marketing fluff, no emoji, no
   exclamation marks, no "we're excited".
5. **Format**:
   - Start with a one-line summary sentence of the release theme if there is a
     clear one; otherwise jump straight to the section.
   - Group items into sections using literal Markdown level-3 headings:
     `### New` for features/enhancements, `### Fixed` for bug fixes, and
     optionally `### Improved` for non-feature, non-bug enhancements. Omit a
     section if it has no items. Always use the `### ` heading syntax — never
     bold-paragraph forms like `**New**` or `**Fixed**`, and never `## `
     (which is reserved for the version header).
   - Use a flat bullet list (`-`) within each section.
   - Each bullet should be one or two sentences maximum.
   - End with nothing — no sign-off, no footer.
6. **Length**: aim for 3-8 bullets total. Merge trivial items. Omit if truly
   nothing is user-facing (output a single bullet: "- Internal improvements
   and stability fixes.").
7. **Language**: English only.
8. Output **only** the Markdown content. No preamble, no code fences.
PROMPT
)"

  local notes
  notes="$(claude -p \
    --model sonnet \
    --allowedTools "" \
    --output-format text \
    "$prompt

--- RAW CONTEXT ---
$(cat "$raw_context")
--- END ---" 2>/dev/null || true)"
  rm -f "$raw_context"

  if [[ -n "$notes" ]] && [[ "$(echo "$notes" | wc -l)" -ge 2 ]]; then
    echo "$notes"
    return 0
  fi
  return 1
}

generate_fallback_notes() {
  local range="$1"
  if [[ -n "$range" ]]; then
    gh api "repos/$REPO/releases/generate-notes" \
      -f tag_name="$TAG" -f previous_tag_name="$PREV_TAG" \
      --jq '.body' 2>/dev/null || \
    git log --pretty=format:'- %s' "$range"
  else
    git log --pretty=format:'- %s' -20
  fi
}

# ── Validation ───────────────────────────────────────────────────────────────

# Lint a release-notes file against the CHANGELOG format used by Prowl-Site.
# Returns 0 on clean, 1 if violations were found (also prints them).
# Section headings must be `### New` / `### Fixed` / `### Improved` (level 3)
# so they sit one level below the `## [VERSION]` header that release.sh
# prepends. Bold paragraphs (`**Fixed**`) and `## Fixed` are both rejected:
# the site CSS targets `:global(h3)`, so anything else renders unstyled.
lint_release_notes() {
  local file="$1"
  local violations=()

  # Bold-paragraph section headers (whole-line)
  if grep -nE '^\*\*(New|Fixed|Improved)\*\*[[:space:]]*$' "$file" >/dev/null; then
    while IFS= read -r line; do
      violations+=("$line  (use '### …' instead of bold paragraph)")
    done < <(grep -nE '^\*\*(New|Fixed|Improved)\*\*[[:space:]]*$' "$file")
  fi

  # Level-2 section headers (collide with the version header)
  if grep -nE '^## (New|Fixed|Improved)[[:space:]]*$' "$file" >/dev/null; then
    while IFS= read -r line; do
      violations+=("$line  (use '### …' instead of '## …')")
    done < <(grep -nE '^## (New|Fixed|Improved)[[:space:]]*$' "$file")
  fi

  if [[ ${#violations[@]} -gt 0 ]]; then
    echo "release-notes format violations in $file:" >&2
    printf '  %s\n' "${violations[@]}" >&2
    return 1
  fi
  return 0
}

# ── Generate ─────────────────────────────────────────────────────────────────

NOTES_FILE="build/release-notes.md"
mkdir -p build

if [[ -n "$RANGE" ]]; then
  if command -v claude >/dev/null 2>&1; then
    log "generating release notes with LLM..."
    if generate_llm_notes "$RANGE" > "$NOTES_FILE"; then
      log "release notes generated by LLM"
    else
      log "LLM generation failed, falling back to GitHub auto-notes..."
      generate_fallback_notes "$RANGE" > "$NOTES_FILE"
    fi
  else
    generate_fallback_notes "$RANGE" > "$NOTES_FILE"
  fi
else
  generate_fallback_notes "" > "$NOTES_FILE"
fi

echo
echo "──── Release Notes ($VERSION) ────"
cat "$NOTES_FILE"
echo "──────────────────────────────────"
echo
log "saved to $NOTES_FILE"

if ! lint_release_notes "$NOTES_FILE"; then
  log "fix the headings above (use '### New' / '### Fixed' / '### Improved'),"
  log "then re-run this script or edit $NOTES_FILE before invoking release.sh."
  exit 1
fi

log "review and edit the file if needed, then run:"
log "  ./scripts/release.sh $VERSION"